Field of the Invention
The present invention relates to thin film transistor arrays, more particularly to a thin film transistor array suitable for a flexible substrate and a printing method.
Discussion of the Background
Thin film transistor (TFT) arrays including amorphous silicon (a-Si) and poly silicon (Poly-Si) provided on a glass substrate have been manufactured based on integrated circuit technique and transistors by using semiconductor substrate. The thin film transistor has been applied to liquid crystal display devices or electrophoretic display devices (non-patent literature 1). As a TFT, for example, a configuration as shown in FIG. 11 is employed (In FIG. 11, a shape of the semiconductor is not clearly illustrated). The TFT serves as a switch such that a signal voltage applied at a source wiring 4′ is written into a pixel electrode 7 connected to a drain 5 when the TFT turns ON due to a selection voltage being applied at a gate wiring 2′. The voltage written is held at a storage capacitor constituted by the pixel electrode 7, a gate insulation layer and a capacitor electrode 10. The gate insulation layer is located at an upper layer side from a gate electrode 2, a gate wiring 2′ and a capacitor wiring 10′ and located at a lower layer side from a source electrode 4, the source wiring 4′, a drain electrode 5, the pixel electrode 7 and a semiconductor pattern which is not shown. At the capacitor electrode 10, voltage is applied via the capacitor wiring 10′. In a case of TFT arrays, since the source or drain function of the electrode changes depending on the polarity of the writing voltage, the electrode name of either source or drain cannot be determined only based on the feature of operation. Hence, conveniently, one side is called a source and the other side is called a drain independently of the function. According to the present invention, a side connected to the wiring is called a source and the other side is called a drain.    PTL 1: International Publication Number 2010/107027    NPL 1: Shoichi Matsumoto: “Liquid Crystal Display Technology: Active Matrix LCDs” Sangyo Tosho, published on November 1996, Page 55